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use crate::{Error, Result};
pub(crate) struct Tokenizer<'s> {
input: &'s str,
chars: std::str::Chars<'s>,
char: Option<char>,
pos: usize,
}
#[derive(Debug, PartialEq)]
pub(crate) enum Token<'s> {
OpenBracket,
CloseBracket,
OpenBrace,
CloseBrace,
Colon,
String(&'s str),
Number(&'s str),
Bool(bool),
At,
Comment,
Eof,
}
impl<'s> Token<'s> {
pub fn type_name(&self) -> String {
match self {
Token::OpenBracket => "BRACKET_OPEN",
Token::CloseBracket => "BRACKET_CLOSE",
Token::OpenBrace => "BRACE_OPEN",
Token::CloseBrace => "BRACE_CLOSE",
Token::Colon => "COLON",
Token::String(_) => "STRING",
Token::Number(_) => "NUMBER",
Token::Bool(_) => "BOOL",
Token::Comment => "COMMENT",
Token::At => "AT",
Token::Eof => "EOF",
}
.to_string()
}
}
impl<'s> Tokenizer<'s> {
pub fn new(input: &'s str) -> Tokenizer<'s> {
let mut chars = input.chars();
let char = chars.next();
Tokenizer {
input,
chars,
char,
pos: 0,
}
}
pub fn next(&mut self) -> Result<Token<'s>> {
self.skip_whitespace();
let r = match self.char {
None => Ok(Token::Eof),
Some(c) => match c {
'[' => {
self.next_char();
Ok(Token::OpenBracket)
}
']' => {
self.next_char();
Ok(Token::CloseBracket)
}
'{' => {
self.next_char();
Ok(Token::OpenBrace)
}
'}' => {
self.next_char();
Ok(Token::CloseBrace)
}
':' => {
self.next_char();
Ok(Token::Colon)
}
'@' => {
self.next_char();
Ok(Token::At)
}
'#' => {
self.next_char();
while let Some(c) = self.char {
if c == '\n' {
break;
}
self.next_char();
}
Ok(Token::Comment)
}
'"' => {
self.next_char();
let start = self.pos;
while let Some(c) = self.char {
if c == '"' {
break;
}
self.next_char();
}
let end = self.pos;
self.next_char();
let s = &self.input[start..end];
Ok(Token::String(s))
}
'0'..='9' => {
let start = self.pos;
while let Some(c) = self.char {
if !c.is_ascii_digit() && c != '.' {
break;
}
self.next_char();
}
let end = self.pos;
let s = &self.input[start..end];
Ok(Token::Number(s))
}
c if c.is_alphabetic()
|| c == '_'
|| c == '-'
|| c == '+'
|| c == '.'
|| c == ','
|| c == '/'
|| c == '\\' =>
{
let start = self.pos;
while let Some(c) = self.char {
if !c.is_alphanumeric() && c != '_' {
break;
}
self.next_char();
}
let end = self.pos;
let s = &self.input[start..end];
if s == "true" {
return Ok(Token::Bool(true));
} else if s == "false" {
return Ok(Token::Bool(false));
}
Ok(Token::String(s))
}
_ => Err(Error::UnexpectedChar(c)),
},
};
r
}
fn skip_whitespace(&mut self) {
while let Some(c) = self.char {
if !c.is_whitespace() {
break;
}
self.next_char();
}
}
fn next_char(&mut self) {
self.pos += self.char.map(|c| c.len_utf8()).unwrap_or(0);
self.char = self.chars.next();
}
}